With the widespread use of lighting equipment, lighting power has also been greatly developed, such as LED power can change the output power in response to the dimmer, thereby changing the brightness of the LED lamps.
Since LED lamps usually contain an array of LEDs, in order to ensure high matching between the LEDs and the consistency of the dimming effect, the LED lamps must be driven by constant current sources, and the current must be strictly controlled.
However, the output of the dimmer is often an angle-missing phase-shifted sinusoidal wave containing high-order harmonics when the dimmer is performing phase-cut dimming. The effective value of the output voltage has a nonlinear relationship with the conduction angle, which usually causes the circuit current unstable, causing the lamp to flicker, uneven illumination or burned damage, etc. The existing power supply has no good corresponding treatment measures; at the same time, when the dimmer performs phase-cut dimming, it is easy to cause a sudden voltage change, further causing circuit instability. After the rectification and filtering of the mains, the capacitor will store a certain amount of electricity, resulting in that the bus voltage does not fall to the zero level, and then the judgment of the high voltage phase angle of the input alternating current is affected. As a result, the voltage amplitude range of the output to the lamp is small, and the lamp cannot conduct depth dimming in a wide range.